1. Technical Field
This invention relates to connector plates sometimes called nailer plates, having a plurality of pairs of nail-like teeth perpendicular to the plane of the plate, struck therefrom, and having sharp knife-like edges on their outermost ends.
2. Description of the Prior Art
Connector plates of various dimensions for various purposes may be seen in U.S. Pat. Nos. 494,882, 3,225,643, 3,242,788, 3,731,583 and 4,209,265.
In U.S. Pat. No. 493,882, teeth termed "projections D" are formed in oppositely disposed relation in a metal plate and guards E are illustrated in the opposite ends of an L-shaped area of the plate from which they are formed. The teeth D or depending projections have continuous edges formed when a die stamps the same from the plate. The guards E are similarly formed and all of the edges of both the teeth or depending projections and the guards are those framed by the severence of the metal of the plate when the forming die strikes the same therefrom.
In U.S. Pat. No. 3,242,788, oppositely disposed pairs of teeth 14 and 14A are struck from a metal plate in which slits 16 and 17 are first formed so that the forming die need only bend the teeth to right angled positions with respect to the plane of the plate from which they are formed. The several edges of the teeth are those formed by the initial stamping die forming the slits in the metal plate.
The several other prior art patents mentioned hereinbefore form the teeth individually with a single die stamping operation and again the teeth have the usual edge configurations which results when sheet metal is torn by a stamping die.
The present invention forms each of the opposed pairs of teeth from one of a plurality of elongated rectangular areas in the sheet metal plate in which grooves have been initially formed by a first die diagonally with respect to the elongated rectangular area from which the opposed pair of teeth are to be formed by a stamping die. The diagonal grooves are preferably V-shaped in cross section and extend at least half way into the sheet metal plate and form sharp beveled surfaces which become sharp beveled edges on the ends of each of the teeth subsequently struck from the area. The resultant teeth, which are perpendicular to the plane of the sheet metal from which they are struck, have oppositely inclined outermost end portions which are the sharpened areas formed by the initial diagonally positioned grooves. Connector plates having teeth so formed require considerably less pressure to be engaged in connecting wooden members to be joined by the connector plates and completely avoid the previous tendency of teeth or nail-like projections of nailer plates as heretofore formed to tear or destroy an area of the wooden members larger than the area actually occupied by the teeth or nail-like projections.